Heat-treating apparatus



Feb, 10, 1946. o. HESS 2,435,923

HEAT TREATING APPARATUS Filed Dec. 14; 1944 w/7w$$ 7 BY a w Patented Feb. 10, 1948 Frederic 0. Boss, Philadelphia, Pa., assignor to Selas Corporation of America, Philadelphia, I la., a corporation of Pennsylvania Application'December-l i, 1944, Serial No. 568,149 4Glaims. (01.263 2) j luy invention" relates .to heat treating metallic bodies, especially ferrous metallic bodies 'containing carbon, and it is an object bf the invention to provide an improvement for'selectively heat treating metallic bodies by radiant heat, as will appear from the Iollowingdescription and ac'-' companying drawing forming apart of this specification. In the drawings Figure 1 is a more or less diagrammatic illustration '0! the apparatus for practicing the invention; and Figure 2 is a viewtaken on' line 2-2 of Figure 1.

"In the drawingyapparatus embodylng'the in-" vntion is'shown for selectively heat treating the hub and'rim portions 10 and ii; respectively, of a pulley wheel I 2'formed of ferrous metal. 'The wheel I2 during heat treatment is adapted to be supported in a horizontal position on work sup porting structure including aplate H and a umberof posts 15 extending upwardly therefrom. The wheel l2 rests upon'the upper ends of the posts 15 f the supporting structure which is adapted to berotated in any suitable '{manner (not-shown), 5 The work supporting structure is also adapted to be lowered from the positiomsh'own in the drawing so that a heat treated wheel may be removed from the'posts-ISand another pulley wheel positioned on the; posts. To facilitate removal of a heat treated wheel an annular "ring is; which is pivoted at n. isnorinally held in 'a' horizontal position in; any suitable manner below the upper ends of posts I5. When the posts l5 of the work supporting structure are moved downwardly, the heat treated wheel I2 is held back onthe ring I6 as the upper ends of the post l5 pass below the ring. 'When this occurs, the ring lfi may be tilteddownwardly about the pivot I1 to permitthe heat treated wheel to slide into a body of quenching liquid or into position" for spray quenching, so as to harden the-heat treated hub and rim portions Ill and l I; respec-* tively.

w'I'he huba portion I0 is adapted to be. heated,

by a heating unit I 8 comprising a pair 'of. gas.-

fired radiators Ill and -2ll=in' face to face-releation.- uThe radiators l9 and 20 are alike, and, as diagrammatically shown, each'ls of parabolic form andjinclude'sa distributor cap 2! which is connected to a nipple 22"extending to the rear of a :block 23 of ceramic material forming the-radia-, ton: The blocks-23 may be provided with hollow jackets 24, through Whichasuitable cooling liquid is -.circulated. to prevent gexcessive heating'ofithe-rearportion'of the: blocks 23.

The. :top radiator 1:95. is stationary .while the s bottom radiator ZBJlsmounted at the upper end of:ahollow post 25 which isvertically movable, whereby the bottom 'radiatorfltmay be loweredfrom the positionshownjn the drawing to the; dotted line positionat 25 below the ring l6.- Suchvertical movement :of the bottom radiator '20 is. necessary in order to-allow the heat treated pul-; ley l2 to be lowered onto the ring 16 in themanner described above. A suitable gas mixture is deliveredto the radiators I9 and 2|} from a source of supply, and the mixture for the bottom radiator passes upwardly thereto through;

the hollow post 25 to which the gas mixture is supplied at 21... i V a i l The rim portion: II is adapted .to be heated by one or more heating units 28 each of which extends for about-aboutthe rim of the pulleywheel l2. fractory lining 29 which ,isclosely adjacent to the rim portion H and conforms to the -curvature of the latter. to;provide a narrow-@9930; therebetween. The lining 29 is formed by a 1101-. low structure 3| ofcerami'c material providing a combustion chamber 32 having a restrictedout-g;

let 33 The restrictedoutlet =33 is in the, form oi a'narrow slot which is midway between the toe and bottom edges of: the lining 29 and extends lengthwise ofthe: lining to regions closely adjacent the ends thereof. a V

The hollow refractory structure 3i is secured to a hollow base "member 34 forming an inlet chamber 35, and between the inlet chamber 35 and combustion chamber 32 is provided an orifice wall having a plurality of orifices. or openings 36 therein. In order to prevent excessive heating oflthe structure 28, -.a hollowjacket 31 is provided; about the latter through which a cooling-liquid;

may be circulated. H When a pulley wheel;-l'2 isto be heat treated, it "is: positioned on the posts; {5- inthemanner shown,lnejthe-edrawing adjacent to the heatingunits Iii-and 28-.'-- The gas mixture is supplied un der pressure"from'thesource of supply- "to the radiatorslfl and 2mm eachof whicha number" of small gas'rstreams are produced by the caps 2|. Combustion of the gas streams is effected at the caps 21 toproduce a numberof gas flames;-

and the heat developed by such combustion heats the radiators to-a highly radian t condition The radiators l9 and 20 are. closely adjacent to eachother to provide a narrow space 39 therebetween which restricts outward flow of the heated gases from the combustion-space formedbythe radia tors, so that combustion may beaocomplished in the d a o eta P es ure; e 'r ha aim Th heating unit 28 includes .a "re pheric. The excess pressure maintained in the combustion space, together with the highly radiant condition of the radiators to which the gas mixture is subjected, intensifies the combustion reaction to produce heated gases at a very high temperature which pass through the narrow space 39 into the gap Ml between the inner surface of hub I and thei'refractory linings 3H at ithe'outer' surfaces "of thebl'ock's 23 adjacent 'toth'e space The lining ll formed at the outer side surface of each block 23 is associated with theradiators I9 and 20, and, since the heated gases are discharged into the gap 40 at" a temperature pm.c-

tically equal to the temperaturein-the radiators and when the chemical reaction of combustion is substantially completed; the linings are heated to a highly radiant condition by the heated gases which sweep over the lining at a high'veloc ity and in intimate contact therewith. Radiant heat waves are projected from the incandescent linings M to-the'- inner surface of hub. in: at close range theretoto effect he'ating-s of "the latter. In addition," heat is liberated from-tthe: high temperature *gases which spread out inrthergap zand come in contactwith the inner-surface of the hub in, so that =radiant heatingfof th'e hub is augmented by I convection. heating.

'-When *a mixture of air' an'd ordinarycitygas i's' employed, for example, the linings 41 may be heated to r a w'liite incandescent "itemp'erature "of 2850' F; or higher and practically-equal toithe temperature at which combustion is accomplished in the radiators I9 and 2!). Undernormaliopeb ating conditions the marrow kerf-like space 339 between the =radiators mayrdevelo'p such a :back pressure that -th'e 'gases in' the combustion :space formed 'by the radiators :may the :maintained at a pressure varying -from' ten' to sixty-finches of water column in excess oi -the pressurezatthe' dischargeend of the outlet formed by rthe space 39'.

Thus, by maintaining' 'thezpressure "of the heated gases in the space at a pressure-rv above that dfatmospheric, 'thetrate-mfsupply of the gas mixture to the "radiators 1-9 "and .21] r is adjusted-"so 2 that combustion may be accomplished at -the :r-adi'at'ors rat a. correspondingly higher pressure. The combined radiantiandxconvection1 Heating coritributesto the :rapid' rate "of heat transfert'o the iwork and'Zthe-tfast .heati penetration'" efiected. :In heating arworkmiece likethehub l ll, 'for 'example ain whi'chathecgap dil-smay be in the neigh'borhooilrof /4:to.' /2-inch; the. hub can i be heated :to the :"crit'rcal hardening temperature "of' 1'5-50" F; to 16507 in vabouta minute or 'less when using a mixture of air 'and :ordinary city gas.

While heating: of "the hubp'ortion [flisbcing'accomplished by the heating unit l8, thefimportion t'l may be heatedat thesame time'tbyithe' heating unit '28; "The :niixture is supplied under pressure to the' ir'ilet chamber 3 5 ofheating'unit 28 and'passes through the openings' 36 into the chamber "-32 in which combustion of the small "subdivided gas streams is accomplished. Tlie 'fiames maintained in combustion' chamber 32 e'fiect'such heating "of -the inner refractory wall surface of the-chamber that' the "latter is heated 'toa highly" radiant condition; Due -to heatingthe inner' wall surface or' chamber 32 'to' a' high incandescent temperature, and subjecting the.;gasfmixtureentering-the chamber to'intense heat' radiated: from "the incandescent wall surface, "substantially complete combustion of the ature of 2850 F. and higher. Due to such heatdngthegases-expand over six fold and at a rate directly proportional to increase in absolute temperature." Invi'ewsofthe fact that the combusg tion ofthe'gas' mixture is accomplished prac- -ticaily-entirly-within chamber 32 and the gases undergo considerable expansion, relatively large volumes of heated gases are discharged from chamber 32 in the form of a gas stream having an average velocity of 700 feet per second and even higher. inthe operation of the. heating unit I8 just described,-the-restricted .=outlet' .i3 may develop such aback pressure that the gases in-chamber-32 may -bezmaintained at apressure' varying from ten :tosixty inches of water column inexcess of-the .pressure-at'the discharge end of. the :out-let. -By 'maintaining ;.the chamber '32 :at: suchan excess pressure,--the:rate of combustion in the chamber iiS accelerated andthetemperature at whichcombustion takes place is in-.-

creased, so that heated-gases are made available for heating work pieces to the :hardening temperature in the shortest length of I time possible. I

The high temperature stream of. heated :gases; producedaby heating unit 28 is:utilizedzto aocom plishselective heat treating inianropensarrange ment by-causingthese heated-gases to heat toa highly radiant condition-the refractorylining-:29.

Suchzheating "of .theklining- 294s. accomplished by providing the narrow gap :30 between .the lin-- ing.and'the rim H-ofthe pulley wheel l2; When asmixture=of air and ordinary-city gas is em ployed, the lining 29 may be heated to a-white incandescent temperature of"2850 F. and higher. Such heating i of. the. lining is .--accomplished :by

the gases which 1. spread out and completely .fill the: gap 30. .In addition, :these high temperature gases-which; flow at a=relatively high velocity, come in (intimate contact with the surface portions of rim H to.-be heatedand :contribute to the high rate ofrheat transfer to the 1 work.

In view-of the foregoing,-it wil1 now be understood that an improvement has been provided for heat treating and hardening metallic bodies by combined-radiant and convection heating in what maybe referred to as open arrangements.

Eurther, the heat may "be-applied to the work:

uniformly .and in relatively .short .heating rtimes. In viewof :the. relatively short-heatingatimes requiredand the fact that many :heattreating and 1 hardening roperations can be accomplished with gas mixtures of air and ordinary gas, likeicity gas and naturalgas, .ior example, considerable economy is :effected" .in heating 'work to elevated T temperatures in accordance :with the invention.-

This 1' application is a division 'ofimy copending application Serial No. .4-82',69'7; filed "April 12, 1942, entitled Heat treatmen which'lis itum is a" continuationsin-part 0f my tcopending application Serial No. '459",680,1fi1e'd September 25,1942, entitled Method -.of and apparatus for-heat" treating metallic bodies.

While a single "embodiment :of ithe invention has been shown and idescribed, :it I will :b'er:appar ent that modifications andachangessmayb'e made '5 without departing from the spirit and scope of the invention, as pointed out in the following claims. I

What is claimed is:

1. Apparatus for heat treating a surface of a cylindrical-shaped metallic body, such as the hub or peripheral surface thereof, for example, comprising rotatable means for supporting the body, structure including a wall having a face or lining adapted to be positioned face to face'with and overlying the surface at close range thereto, said lining being at least as wide as the surface and curved so that, when it is positioned closely adjacent tothe surface, a narrow gap is formed therebetween, the portion of said lining adapted to overlie the surface being formed entirely of high temperature refractory material, said wall having an elongated slot intermediate its edges in a plane transverse to the axis of the cylindrical-shaped body when the latter-is supported in a heating position by said rotatable means, and means communicating with said slot for produc ing heated products of combustion from a combustible gas mixture and for flowing such products of combustion through said slot only when the chemical reaction of combustion of the mixture is substantially completed and while the products of combustion are practically at the temperature at which combustion is accomplished, said lining being heated to a highly incandescent condition by the heated products of combustion passing into the gap through the slot to effect radiant heating of the surface when the body is being rotated which is augmented by heat liberated from the products of combustion passing through the gap in intimate contact with the surface.

2. Apparatus for heat treating a cylindrical surface of a metallic body comprising rotatable means for supporting the body, structure including a wall having a curved face or lining adapted to be positioned closely adlacent'to and overlying the surface so that a narrow gap is formed therebetween, the portion of said lining adapted to overlie the surface being formed entirely of high temperature refractory material, said wall having an elongated slot intermediate its edges in a plane transverse to the axis of the cylindrical surface when the body is supported in a heating position by said rotatable means, and means for producing heated products of combustion from a combustible gas mixture and flowing such products of combustion through said slot only when the chemical reaction ofcombustion of the mixture is substantially completed and while the products of combustion are practically at the temperature at which combustion is accomplished, said lining being heated to a highly incandescent condition by the heated products of combustion passing into the gap through the slot to effect radiant heat heating of the cylindrical surface when the body is being rotated which is augmented by heat liberated from the products of combustion passing through the gap and in intimate contact with the surface.

3. Apparatus for heat treating .work comprising rotatable means for supporting the work, structure including a wallhaving a curved face or lining adapted to be positioned closely adjacent to the work so that a narrow space is formed between it and the work it overlies when the work is being rotated. the Portion of said lining adapted to overlie the surface being formed entirely of high temperature refractory material, and a surface of means for producing heated products of combustion from a combustible gas mixture and utilizing such heatedproducts of combustion only when the chemical reaction of combustion is substantially completed and while the products of combustion are practically at the temperature at which combustion is accomplished to heat said lining to a highly incandescent condition to effect radiant heating of the work when the latter is moved with respect to said lining by said rotatable means.

4. Apparatus for heat treating work comprising rotatable means for supporting the work, structure including a wallhaving a curved face or lining adapted to be positioned in a plane substantially parallel to the axis of said rotatable 'means and closely adjacent to the work so that a narrow space is formed between it and a surface of the work it overlies when the work is being rotated, the portion of said lining adapted to overlie the surface being formed of high temperature refractory material, and burner means for producing heated products of combustion from a combustible mixture and, utilizing such heated products of combustion only when the chemical reaction of combustion is substantially completed and while the products of combustion are practically at the temperature at which combustion is accomplished to heat said lining to a highly incandescent condition whereby, when the work is moved with respect to said lining and burner means by said rotatable means, heating of the work is effected by heat radiated from said lining and by the heated products of combustion.

FREDERIC O. HESS.

REFERENCES CITED The following references are of record in the file of this patent:

Certificate of Correction Patent No. 2,435,923. February 10, 1948.

FREDERIC O. HESS It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Column 6, lines 9 and 10, claim 3, strike out the Words a surface of and insert the same after and and before the in line 6, same claim; and that the said Letters Patent should be read with these rgfrfirections therein that the same may conform to the record of the casein the Patent Signed and sealed this 27th day of April, A. D. 1948.

THOMAS F. MURPHY,

Assistant Oommz'ssz'oner of Patents. 

